M.S. Thesis Presentation by Scott Daniel McDermott
Wednesday, June 16, 1999

(Dr. Bert Bras, advisor)

"Development of a Haptically Enabled Disassembly Simulation Environment"

Abstract

The ability to service, reuse and recycle product components reduces the product’s environmental impact.  To accomplish these tasks more efficiently, ‘ease of disassembly’ should be a product design goal. Not unlike other design goals, the examination of product disassembly in a virtual environment (VE) provides a number of benefits.  Primarily, it allows evaluation early in the design process, increasing its impact on the final design, and it eliminates the time, cost, and material associated with the construction of physical prototypes.

Typically, however, VE’s constrain the user to one sense, sight, and two dimensions, the table upon which the mouse rests.  Even Virtual Reality (VR) environments do not solve the problem.  Despite their visually immersive capabilities, their effectiveness is limited by the simple fact that “there is nothing to touch.” The introduction of a haptic interface into the VE allows users to incorporate both a third dimension and a second sense, that of touch, into their work.

A haptic interface is a peripheral device that measures forces incurred by a user’s avatar (the user’s representation in a virtual environment) in 3-D space and then exerts those forces on the actual user, allowing the user to feel and manipulate objects.  Thus, a disassembly simulation that provides haptic feedback allows designers to utilize that 3-D tactile information and perhaps generate disassembly sequences more effectively. As this is a relatively new technology, however, an open area of research is the evaluation of the viability of this technology as an integrated component in such environment.

In pursuit of this objective, a testbed application was developed.  In this thesis, the basic computer architecture of the application is presented, including its interface with commercial CAD systems.  Also explained are some constraints unique to haptic simulation and the methods employed to help meet these constraints for real-time disassembly simulation.  Further, the use of collision detection and response methods to prevent part interpenetration is discussed.  Two case studies are presented as a means to evaluate the application’s effectiveness.